Lesson 8 Real-time Clock ModuleΒΆ

Introduction

Nowadays there are many popular serial clock circuits such as DS1302, DS1307, PCF8485, etc. They are widely used for simple interface, low cost, and ease of use. In this lesson, we will use the DS1302 real-time clock (RTC) module to obtain current date and time.

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Components

  • 1 * SunFounder Uno board

  • 1 * USB data cable

  • 1 * RTC-DS1302 module

  • 1 * I2C LCD1602 module

  • 1 * 5-Pin anti-reverse cable

  • 1 * 4-Pin anti-reverse cable

  • 1 * Dupont wire (F to F)

Principle

DS1302 is a trickle charging clock chip, launched by DALLAS in America. With a built-in real-time clock/calendar and a 31-byte static RAM, it can communicate with MCU through simple serial ports. The real-time clock/calendar circuit provides information about second, minute, hour, day, week, month, and year. DS1302 can automatically adjust the number of days per month and days in leap year. You can determine to use a 24-hour or 12-hour system by AM/PM selection. It can simply communicate with MCU in synchronous serial way and only needs to use three port cables: Reset (RST) cable, I/O data (SDA) cable and serial clock (SCL) cable. The schematic diagram of the module:

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Experimental Procedures

Step 1: Build the circuit

The wiring between DS1302 and SunFounder Uno board is as shown below:

DS1302

SunFounder Uno

SCL

7

SDA

6

RST

5

VCC

3.3V

GND

GND
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Step 2: Open the code file

Step 3: Select correct Board and Port

Step 4: Upload the sketch to the SunFounder Uno board

Code

Now, you can see the current date and time information displayed on the I2C LCD1602.

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